Forest conversion may exert multiple selective pressures and lead to morphological differences among organisms. Despite considerable research on morphological responses to forest loss, gaps remain regarding the effects of practices such as forestry on insect morphology. Here, we compared the intraspecific morphological variation in two damselfly species (Acanthagrion lancea and Telebasis carmesina; Odonata, Coenagrionidae) between mixed-ombrophilous forests (MOF) and tree plantations in the Brazilian Atlantic Forest. We assessed body shape (head and thorax width, abdominal length) and wing morphology traits (area and aspect ratio) and predicted that trait variability would be reduced in plantations. In both species, trait variation patterns differed between forest types and were lower in plantations. Specific traits also differed between forest types: A. lancea showed wider thoraces, longer abdomens and larger wing areas in MOF, while T. carmesina showed higher wing area and aspect ratio in plantations. Differences in damselfly morphological variability are likely the outcome of limited plant diversity and altered microclimate conditions in plantations. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.

Aquatic insects are key to wetland ecological functioning, and the distribution of amphibious insects such as Odonata jointly depends on environmental conditions in the aquatic and terrestrial settings. Therefore, untangling the relative effects of within-wetland and landscape composition can help predict the responses of Odonata to environmental alterations in wetlands. Using data from 19 wetlands spanning over the southern Brazilian Pampa (center-western Rio Grande do Sul state), we assessed the relative importance of water chemistry and land-cover variables to the richness and composition of larval Odonata assemblages (and suborders Anisoptera and Zygoptera). Anisoptera richness decreased with pH and bare soil area. Water pH and areas of bare soil, mosaic of agricultural land use, and waterbodies land cover were the main drivers of Odonata and Zygoptera composition. Our results indicate that land cover is the main driver of the assemblage structure of larval Odonata, although a complex interplay of mechanisms associated with land conversion and water quality drive the distribution of larval Odonata in freshwater wetlands of the Brazilian Pampa. The major implication of our findings is that land cover modification is the major threat to Odonata distribution in Pampean wetlands, with potential impacts on the trophic structure and functioning of these ecosystems. © 2024 The Ecological Society of Japan.

Dragonflies (Odonata) are ancient and familiar insects with a deep and strong cultural association with humans. They have an aquatic larval stage and an aerial adult stage, meaning that they respond to ecological conditions in both freshwater and the adjacent land surface. Currently, 16% of dragonflies are threatened. Overall, they face several threats, especially habitat loss, landscape transformation, pollution, altered hydrology, spread of invasive alien species, as well as certain geographic-specific threats. Overarching these threats, which can be interactive with each other, is the issue of global climate change and attendant extreme weather events. While many localised and habitat specialist species are under extreme threat, some other dragonfly species, mostly habitat generalists, benefit from certain moderate human activities, especially the creation of high-quality artificial ponds. As well-researched insects, dragonflies play an important role in the protection of freshwater and riparian ecosystems. Dragonfly assemblages have great value as sentinels of both deteriorating environmental conditions and ecosystem recovery following restoration. While similar findings on both threats and conservation actions are emerging across the world, certain ecosystems require targeted approaches. Above all, dragonflies must be included more widely in general biodiversity conservation activities and policies. Overall, dragonflies are important targets, tools and model organisms for conservation action, and they can act as potential surrogates for other taxa that also depend on high water and riparian zone quality. While research has paved the way to address these challenges, including the use of new technologies, we now urge that dragonflies be included more strongly in policy and management associated with both freshwater and adjacent terrestrial realms. This inclusion is especially effective as dragonflies have great appeal to a diverse community of people from odonatologists (citizen and professional) through to policymakers and managers, all of whom can employ dragonflies to contribute more to freshwater-associated conservation. Finally, we propose an action plan focusing on five action points that address opportunities, and we suggest where dragonflies can play a greater role in freshwater/riparian zone conservation more widely across the world. © 2025 The Author(s). Insect Conservation and Diversity published by John Wiley & Sons Ltd on behalf of Royal Entomological Society.

Streams in South American subtropical grasslands are under increasing environmental pressure. The development of biological indices to assess impacts on streams in this region is important from both conservation and applied perspectives. Metrics based on the Odonata (Insecta) community structure are useful for assessing anthropogenic disturbances in tropical forest streams. However, little is known about the potential of Odonata‐based metrics to assess impacts on streams in nonforest landscapes. Here, we assess the potential of taxonomic ratios of Odonata as tools to assess anthropogenic disturbances in streams across the South Brazilian grasslands. We tested the relationships of ratios between the number of taxa from each suborder (“Zygoptera/Anisoptera” ratios) and between families and genera within each suborder with anthropogenic landcover surrounding each stream. “Zygoptera/Anisoptera” ratios and ratios of the damselfly genus Argia (“Argia/Zygoptera”) were negatively related to anthropogenic land cover, while “Libellulidae/other Anisoptera” ratios were positively related. Inaddition, threshold analysis found that “Argia/Zygoptera” ratios were negative indicators of anthropogenic land cover. Our study expands the potential of taxonomic ratios of Odonata as a biomonitoring tool for the integrity of subtropical non‐forest streams, such as those of the South Brazilian grasslands. Moreover, taxonomic ratios based on the richness of lotic‐specialist taxa within the suborder Zygoptera can reflect the degree of anthropogenic landscape disturbances. Our results contribute to developing biological indices to assess the environmental impacts of land‐use changes in streams in the Global South.

Studying how habitat conversion influences morphology is essential for predicting long-term viability of insect populations. However, there is limited knowledge of how the morphology of aquatic insects (such as Odonata) varies among habitat types in fragmented landscapes such as subtropical forests in the Neotropical Region. Here, we test for shape differences in the neotropical dragonfly Erythrodiplax castanea (Burmeister, 1839) (Odonata, Libellulidae) inhabiting native and planted forest habitats in the southern Brazilian Atlantic Rainforest. Specifically, we compared linear morphometric measurements in adult dragonflies found in patches of mixed ombrophilous forests and tree plantations. We measured eight traits (abdominal length, thorax width, fore- and hindwing length and width, fore- and hindwing area and aspect ratio) and used analysis of covariance (with body length as covariate to account for size) to assess variation in each trait between forest types. Models showed that specimens with similar sizes (body lengths) had significant larger values of thorax width, forewing length and aspect ratio in tree plantations than in mixed ombrophilous forest. Shape differences in adult dragonflies are likely explained by the differences in microclimate (insolation, temperature, humidity, wind) and habitat complexity (tree spacing) among mixed ombrophilous forest and tree plantations, suggesting that the processes driving adult odonate establishment differ between forest habitat types. We shed further light on how dragonfly morphology responds to changes in vegetation structure in the southern Atlantic Forest. Our findings can be useful to predict the effects of land cover conversion on dragonflies in South American subtropical forests. © African Association of Insect Scientists 2025.

Human activities such as logging, agriculture, and urbanization can drastically change and limit Odonata species distributions in aquatic and terrestrial environments. These modifications may culminate in extirpations of rare and resident species and homogenization of community composition across space. This chapter reviews how human land use is (re)shaping odonate assemblages and focuses on the impacts from logging, agriculture, and urbanization. Deeper appreciation and analysis of regulatory mechanisms (e.g. vulnerability traits, species interactions, phylogenetic niche conservatism) and background “noise” (e.g. natural heterogeneity, climate change, historical context) will be important in understanding and predicting odonate community responses to ongoing and future landscape alteration.

Farming expansion has negative impacts on freshwater biodiversity. However, the efects of agricultural land use are not similar across taxa and depend on local context. For instance, the impacts of agricultural expansion are understudied in the Neotropics (one of the leading regions in cropland expansion). Knowledge of the effects of agricultural land use on aquatic insects from South American subtropical grasslands (Pampa) is even more incipient. We tested whether landscape modification related to increased agricultural land use was associated with taxonomic homogenization in odonate communities in waterbodies in the Brazilian Pampa. Odonates were collected in waterbodies differing in the main land-use class in their surroundings (cropland or grassland). Cropland and grassland sites differed with respect to their abiotic conditions (water chemistry) and species composition of Odonata. Additionally, we found higher variation in the composition of Odonata (and suborders Anisoptera and Zygoptera separately) in grassland than cropland sites. We found an interplay between agricultural and grassland land uses and the variation in the composition of odonate communities in the Brazilian Pampa. Specifically, landscape modification by agriculture modified the abiotic conditions in the waterbodies, which may have favored species able to establish as larvae under harsher environmental conditions. 

Implications for insect conservation: We suggest that the maintenance of mixed-grassland and cropland land uses in the fields adjacent to waterbodies can limit the negative effects of agricultural encroachment on Odonata communities with respect to biotic homogenization in the Brazilian Pampa. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

Understanding the interactions between protected areas and the surrounding landscape has become a central issue to conservation of biodiversity. The important role of protected areas in the preservation of biodiversity in tropical hotpots is widely recognized, but the role of the landscape surrounding those hotspots is poorly understood, particularly with regard to insects. In this study, we evaluated the species richness, composition, and beta diversity of Odonata assemblages inside and in the surroundings of a protected area in the Atlantic Forest hotspot. Sampling was carried out in the Private Reserve of Natural Heritage Veracel Station and its surroundings in the southern region of Bahia. Forty sites were sampled, 22 within the reserve and 18 in the surrounding areas. We found both a greater total species richness, and a greater richness with regard to the suborder Anisoptera in the surrounding areas. In addition, the species composition differed less between the sampling sites inside the protected area. Some of the species found inside the protected area did, however, make a greater contribution of the individual species to beta diversity (SCDB). Our study suggests that the surroundings of a protected area can contribute to the maintenance of regional diversity of dragonflies, but the protected areas play a vital role in supporting critically endangered species and populations of forest specialists, e.g., phytotelmatous species. Implications for insect conservation: Our results show that the composition of the odonate species assemblages may provide a means to assess the importance of protected areas to Odonata communities. Our study also highlights the importance of PAs to the maintenance of the regional Odonata species pool, especially to forest specialist species and to threatened species. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

The global population structure and dispersal patterns of Pantala flavescens (Fabricius, 1798) are evaluated using a geographically extensive mitochondrial DNA dataset, a more limited samples of nuclear markers, wing isotopic (δ²H) data and a literature review. No spatial or temporal haplotype structure was recovered between the samples. Isotope data suggest that most samples were immigrants at the collection locations. A literature review of migration events for the species confirms regular inter-and intra-continental migrations occur (the majority reported from Asia, Africa and Australasia), with individuals and swarms dispersing thousands of kilometers over land and oceans. Migrations coincide with prevailing winds and seasonal rains, which points to a mechanism we name the “pantropical Pantala conveyor belt”, suggesting widespread gene flow is possible for an aquatic insect with excellent flying ability linked to rapid larval development.